Blue Ivy: What's Behind Beyonce and Jay-Z's Choice of Baby Name?

Beyonce and Jay-Z's baby name, while odd, actually makes sense.

Jan. 9, 2012 — -- Blue Ivy: It's definitely one of the odder celebrity baby names in recent memory (though Alicia Silverstone named her son Bear Blu -- trend alert?), but for Beyonce and Jay-Z, who welcomed their daughter Blue Ivy Carter on Saturday, it makes a lot of sense.

Jay-Z's dropped three albums with "blue" in their titles: "The Blueprint," "The Blueprint 2: The Gift & The Curse," and "The Blueprint 3." He's also penned songs that pay homage to the color, like "Blue Magic" and "Empire State of Mind" in which he raps, "You should know I bleed blue."

He's often seen wearing a New York Yankees hat, which is, of course, blue.

And "Ivy?" People magazine reports that it's a derivitive of the Roman numeral IV and the number 4, which factors prominently in the couple's relationship.

Beyonce's birthday is Sept. 4, Jay-Z's is Dec. 4 (He also named a song "December 4th"). They married on April 4, 2008 and reportedly have matching "IV" tattoos on their wedding fingers. The name of Beyonce's latest album: "4."

The two-day old baby girl has one thing her parents shed long ago, though -- a surname. "'Blue Ivy Carter' is the ONLY one in that family with a last name," Questo, the drummer of The Roots, tweeted today, citing "Late Night with Jimmy Fallon" writer Mike DiCenzo. Sean Carter and Beyonce Knowles effectively left theirs behind when they ascended to super stardom.

Nicknames are already in the works. Rihanna called Blue Ivy "princess carter" in a congratulatory tweet over the weekend, while Solange Knowles, Beyonce's sister, simply dubbed her "The most beautiful girl in the world."